Twenty five nations took part in a U.S.-led naval exercise on Monday (October 30) in waters not far from Iran aimed at training forces to block the transport of weapons of mass destruction and related equipment. The exercise comes as tensions rise between Iran and the West over its nuclear programme, which critics say has as its goal the production of a nuclear bomb. Iran says it is designed to meet energy needs. It also comes three weeks after North Korea conducted a nuclear test and amid increased fears that a proliferation of nuclear technology could make it easier for terrorists to get their hands on an atomic bomb or its components. Italy, the United States, Australia, Britain, France and Bahrain deployed ships and personnel to the drill, part of the U.S. Proliferation Security Initiative (PSI). Other countries, including the United Arab Emirates (UAE), Qatar, Pakistan and South Korea, sent observers. Bahrain, home to the U.S. Navy's Fifth Fleet, was the only Gulf Arab state to take an active role. In the exercise, Bahraini and Italian marines -- accompanied by U.S. experts -- searched a British vessel carrying mock nuclear detonators about 20 miles (32 km) away from Iranian waters in the Gulf. The marines sped through the water in small inflatable bloats and boarded a British vessel, the RFA Brambleleaf, which was designated the suspect ship. Marines armed with machine guns guarded the crew as another team searched the vessel for the detonators. Some countries took part in planning the operation, whereby various intelligence agencies worked on a scenario in which a vessel en-route to the UAE from Europe was suspected of carrying weapons of mass destruction. U.S. Ambassador to Bahrain William Monroe told reporters at a Bahrain naval facility that the drills sent a clear message that proliferation would not be accepted. He said the exercises were significant, being the first of their kind to take place in the Gulf. "Well the significance is that this is the first time we've had one in this region and that just goes to show the more regions and the more areas we have these exercises in, it just shows the more global cooperation we have in this area, and we are concerned about proliferation anywhere and it's very nice and very good and important to see that the proliferation concerns extend around the world including this region," Monroe said. Iran said it was unconcerned about the exercise but warned those participating not to destabilise the region. The Bahraini, Qatari and UAE involvement in the U.S. initiative flies against Iran's call on Sunday (October 29) for regional security to be maintained by countries in the region. Several Middle Eastern countries have endorsed PSI principles this year after visits by U.S. officials to the region were stepped up, a State Department official who declined to be identified said. Sunni Muslim Gulf Arab states have traditionally been wary of Shi'ite Muslim Iran's intentions in the region. Leading Edge was the 25th PSI exercise since U.S. President George W. Bush launched the initiative in 2003. Eighty countries have endorsed PSI principles.